1. Field of the Invention
This invention relates generally to a tendon tension sensor and, more particularly, to a tension sensor for a tendon in a robotic arm where the sensor employs an elastic element through which the tendon is threaded and strain gauges mounted to the elastic element that measure the bending of the elastic element in response to tension on the tendon.
2. Discussion of the Related Art
Dexterous robot systems are known in the art that perform a variety of functions. A dexterous robot system typically includes a robotic arm having fingers and related joints that operate to grasp an object or part for a particular application. In a particular dexterous robot system design, tendons are employed to actuate the fingers where the tendons are coupled to the finger joints. The tension in the tendons provides an indication of the external loads experienced by the fingers. Thus, it is desirable to measure the tension in the tendon to provide a measurement of the load on the fingers.
One known technique for measuring the tension in a robotic tendon employs a strain gauge sensor for measuring the tensile deformation of the tendon. However, the range of tensile forces that are encountered in robotic applications may be so small that strain gauge sensors may not be sensitive enough to provide an accurate measurement.
It is also known in the art to use load cells to measure tension. However, commercially available load cells typically are too large for robotic applications in that they cannot be adequately housed inside of a robotic arm.
Another known design employs an S-shaped elastic element on which a strain gauge is mounted. An end of a tendon is coupled to one end of the S-shaped element and an end of another tendon is coupled to an opposite end of the S-shaped element so that tension on the tendon cause the S-shaped element to deform. This design requires cutting of the tendon and has a relatively large diameter.